The document discusses piecewise defined functions. It defines a piecewise function as one where the function definition changes depending on the interval of x-values. It provides examples of sketching piecewise functions and finding their domains and ranges. Specifically, it gives the examples of the functions y=-2, f(x)=2x for -2<=x<=3, and g(x)=-(3/2)x+1. It also defines a piecewise function as having different expressions on various intervals.